1 Background - mountain.PROJECTS

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TURKU UNIVERSITY DEPARTMENT OF GEOGRAPHY PUBLICATIONS B Nr 4Organisation of dataAll data are organised hierarchically in the OMEGA database as presented in Figure 40. Thebasic unit is Feature, which is the main information carrier. Feature holds a geometricalobject and a set of associated properties (i.e. text, integer, float, binary object with MIMEinformation)and data related metadata. One Feature can be one multi-band satellite image orset of field measurements (i.e. GPR measurements). All Features are organised in FeatureCollections, which is a logical collection of the same data type from same area of interest inthe same co-ordinate system. One Feature Collection can consist of e.g. one type of satelliteimages (i.e. Landsat multi-band) from the same area of interest. Certain Feature Collectionscan be grouped so that they form a Dataset. A Dataset is a logical collection of the same typeof Feature Collections. One Dataset is saved into one Feature Server. Each dataset in theOMEGA database system is represented to the users with the OMEGA Server (Sylvarnes,2002). Table 4 presents the following Datasets used.Table 4. The Datasets used in the OMEGA project.RS_dataAirborneRS_dataSatelliteTerrestrialMeasurementsDataProductsIncludes all image data collected by a sensor platform located in anaircraft. All data is in processed format.Includes all image data collectedby a sensor platform located in asatellite. All data is in processed format.Includes all field measurements. Data is either in original orprocessed format.Includes all products generated from one or more sets of originaldata and observationsThe data collected from partners were saved into several Feature Servers at three locations:NORUT, University of Helsinki and NOVOSAT (Figure 40). A Catalog Server was runningat NORUT. Data were saved into the Feature Servers and OMEGA partners were allowed tobrowse and download the data by using OMEGA Browser.In addition, an internal glacier database (Hysopp) is created at NVE and populated withgeographic and mass balance data for the different glaciers in Svartisen, including Engabreen,Storglombreen and Svartisheibreen. Mass balance data for a total of 46 years has beenregistered here.MetadataEach geographic feature has properties such as acquisition date, producer, aimed purpose,accuracy etc. This kind of information is called metadata. Metadata is information about data.It is desirable for a data user to understand through which processing steps the data has gonethrough, to know the age of the data, who provided the data, what the data actually describes,what the co-ordinate system is etc. All this kind of information is not available as attributes inthe OMEGA database. A certain OMEGA metadata standard was decided upon to describethe necessary information for OMEGA data. The metadata structure is based on the Open GISconsortium’s ISO 19115 standard (OpenGIS, 2001) with some simplifications and additionalmodifications so that the structure meets better the requirements of the OMEGA System.Metadata is implemented as a pdf-sheet that is filled by the data provider using the AdobeAcrobat© software.58
PETRI PELLIKKA AND KARI KAJUUTTI (ED)There are six main metadata descriptor categories in metadata sheet:1 Data description2 Spatial Representation3 Spatial Reference System4 Quality5 Data storage format6 Attribute explanations7 Quide for data userIn total there are 50 – 100 different items in the metadata sheet to be filled. The number ofitems depends on data type (i.e. raster or vector). (Omega Final Report: Appendix 17).FeatureGeometry: RasterProperties:AcqDate: 20010924Owner: UTUFeatureGeometry: RasterProperties:AcqDate: 20020908Owner: UTUFeatureGeometry: VectorProperties:AcqDate: 20010924Owner: UINN.IMGFeatureGeometry: VectorProperties:AcqDate: 20010924Owner: UINN.IMGFeature CollectionLandsat MSFeature CollectionGlaciological measurementsOther datasets (servers)Dataset (=> one server)UINNCatalog serverNORUT ITOther datasets (servers)Figure 39. Structuring the OMEGA glacier data into the GIN terminology. A dataset consists of(possibly) several feature collections, each feature collection consists of several features, and eachfeature has a geometry (vector or raster) with a set of predefined properties and metadata.The metadata is saved into the OMEGA Feature Server together with the actual data. When auser downloads the data from the system, the metadata is downloaded simultaneously. A usercan download also only just the metadata sheet to check e.g. the accuracy of the data.Main mailstones and deliverablesThe main mailstones of the glacier monitoring system are:- Definition of the overall OMEGA System architecture- OMEGA monitoring system- Glacier database- OMEGA Web Service- Furnishment of the OMEGA System with the prodects resulted from WP 3 and 4- Metadata templates59
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1 Background - mountain.PROJECTS

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